you gotta go with what is implied in these pictures dude
He has on a guards uniform so he is obviously in the guard (possibly stationed somewhere he couldn't get home from easily)
Scootaloo is running towards him, he has his forelegs open, quite possibly for a hug, and Cheerilee has tears in her eyes showing she is emotionally touched by this
So obviously, that is Scootaloo's Dad who has come home for some reason or another, and it has been a while since she has seen him
Think of it like one of those many videos where the military parent comes home and surprises their kid